The field of invention is pressure sensors, more particularly pressure sensors for determining pressure changes in a sealed container.
Many incidents of fire, explosion, and ground contamination have occurred at various facilities over the years due to container rupture because of over pressurization. Containers, such as drums, frequently contain hazardous liquid wastes, with the result that the rupture causes the waste material to contaminate the surrounding environment. Drums are often classified into two types, open head and tight head. An open head drum has an open top which is sealed with a lid. A tight head drum has a closed top with bung holes for draining and venting. When sealed, the tight head bung holes are sealed with bung plugs.
Over pressurization may occur as a result of climatic changes causing the drum to be over pressurized, such as may occur should the drum be exposed to strong sunlight. Volatile wastes stored in an area subject to high temperatures may result in pressure build up sometimes being sufficient to cause the drum to burst or rupture. More often, the over pressurized drum ruptures during handling by personnel unaware of the elevated drum pressure.
The increase of gases and vapors in a drum may sometimes be identified due to bulging or deformation prior to the build up reaching a level sufficient to rupture the drum or cause a violent release of material. In many cases, the drums are over packed so that visual signs of over pressurization are not evident. Invasive techniques of determining the internal pressure of a sealed drum is time consuming, may result in the release of toxic material into the atmosphere, and is therefore, often limited to drums exhibiting some bulging.
In many incidents, however, drums become pressurized to the extent that visible deformation has not occurred but personnel transporting and storing drums are unaware of pressurization. Those skilled in the art will recognize a need for a non-intrusive apparatus that will provide an indication of a pressure change inside a sealed container.